Circuit tuning device



Sept. 29, 1953 G. E. MORTON CIRCUIT TUNING DEVICE Filed y 51, 1951INVENTOR.

Arm/FMS 650425: 5 Mom-cw "M, I 1% fiwzq.

m R m NM Patented Sept. 29,1953

CIRCUIT TUNING DEVICE George E. Morton, North Royalton, Ohio, assignorto Designers For Industry,

a. corporation of Ohio Inc., Cleveland, Ohio,

Application May 31, 1951, Serial No. 229,067 3 Claims. (01. 25040) Thisinvention relates to radio circuit tuning devices and, as one of itsobjects, aims to provide an improved device of this kind which is of asimple, economical and compact construction but which will afford verysensitive tuning over a wide range of signal frequencies.

Another object is to provide an improved circuit tuning device of thischaracter embodying a variable inductance and a variable capacitance,and in which a single actuating mechanism of a novel form serves boththe variable inductance and the variable capacitance.

A further object is to provide an improved circuit tuning device of thecharacter mentioned in which the actuating mechanism comprisesrelatively rotatable coaxial sleeves and a carrier member movableaxially thereof, and in which cooperating slot and follower meansproduce the axial movement of the carrier member in response to therelative rotation between the sleeves.

Still another object is to provide an improved tuning device of the kindabove indicated in which the slot means comprises an axial slot in oneof the sleeves and a helical slot in the other sleeve extending incrossing relation to the axial slot, and in which the follower meansincludes a member engaging in both slots at their point of crossingrelation.

The invention can be further briefly summarized as consisting in certainnovel combinations and arrangements of parts hereinafter described andparticularly set out in the claims hereof.

In the accompanying sheet of drawings,

Fig. 1 is a front elevation of a tuning device embodying the presentinvention.

Fig. 2 is a longitudinal vertical section taken through the devicesubstantially as indicated by section line 2-2 of Fig. 1.

Fig. 3 is a transverse section taken through the device substantially onsection line 33 of Fig. 2; and

Fig. 4 is a side elevation showing one of the sleeves of the actuatingmechanism in detached relation.

As one practical embodiment of this invention, the drawing shows theimproved radio circuit tuning device ID as comprising in general avariable inductance device II, a variable capacitance device I2 and anactuating mechanism I3 operable to simultaneously vary the inductanceand capacitance values of the devices II and I2. The tuning device II)also includes a suitable base or support I4 forming a mounting means forthese devices an whic may be a p t on of the chassis I4 and M In theembodiment of the tuning device I 0 here shown, the variable inductancedevice II is mounted on the horizontal wall portion M of the support Itand the actuating device I3 is mounted on the upright wall portion M Thedevices I I, I2 and I3 are disposed in a substantially axially alignedrelation in which the variable capacitance device I2 is disposed betweenthe variable inductance device II and the actuating mechanism I3 and issupported by the latter.

The variable inductance device II is in the form of a hollow coil meanscomprising an inner coil or helix I5 and an outer coil or helix I6disposed in a surrounding coaxial relation to the inner coil. Thisvariable inductance device H also comprises a core member I! which willbe further described hereinafter and which is movable into the hollowcoil means.

The coils I5 and I6 are supported by an insulating sleeve or tube II awith the inner coil I5 disposed inside the sleeve and the outer coil I6disposed around the sleeve. The inner and outer coils I5 and I6 can bein the relation of primary and secondary coils of an inductive couplingdevice or transformer. Although the inductance coil means is here shownas including a plurality of coils I5 and I6, it is not necessary thatthe device always comprise multiple coils inasmuch as the inductancecoil means may comprise a single coil or helix, or may comprise an autotransformer having coil sections inductively coupled by mutualinductance.

The coil means of the inductance device I I can be suitably mounted onthe horizontal wall portion I I of the support I4 as by means of abracket I8 having spaced upright parallel arms I8 and I8 with which theends of the insulating sleeve I I are connected as by engaging inopenings thereof. The inner coil I5 has opposite ends thereof projectingoutwardly therefrom and forming a pair of leads or terminals 19 and 20to which further reference will be made hereinafter. Similarly, theouter coil It has projecting end portions forming another such pair ofleads or terminals 2| and 22.

The core ll of the variable inductance device II is here shown as beingin the form of a stem which is axially movable into and out of themagnetic field of the hollow coil means, preferably by being axiallymovable into and out of the inner coil I5. This core member can be madeof either a non-ferrous metal such as copper or aluminum or can be madefrom a ferrous metal such as iron, but is preferably formed from acombination of finely divided iron such as carbonyl iron and a bindersuch as polyvinyl resin or other suitable plastic. When the core memberis made from such a combinatioin of carbonyl iron and a binder, it canbe readily molded to the desired shape such as the stem ll here shown,and during the use thereof the finely divided iron produces the effectof a laminated core member.

The core member i1 is preferably provided with an insulating cover 25which isolatesthecorestem from metallic contact with the inner coil iswhen this stem is moved into thelatter. The covering 25 can be of anysuitable-'insulating'or' dielectric material, such as polystyrene orother suitable plastic, and can be molded: in,place@on' the core memberin surrounding relation thereto.

The capacitance device [2 comprises an outercapacitance member 2'5 ofsuitable surface area for the capacitance value :desired .and an innercapacitancemember 28 movable relative thereto and also having suitablesurface area- 'Theiouter capacitance member 2:? comprises a sleeve :madeof a metal having good electrical conductivity, preferably a non-ferrousmaterial :such as copper or aluminum, and preferably has a thin platingof silver (not'shown) thereon. The outercapacitance member 2? can besuitably supported, but preferably as here shown, this capacitancemember is supported by being mounted in an insulating sleeve or barrel-249 which is, in turn, supported by the inner end of the actuatingdevice l3.

The mounting sleeve 21! can be formed of a-suitable insulating materialor dielectric, such as polystyrene or any other suitable plastic. Themounting sleeve '29 has the outer end thereof connected with the inner'end of the actuating device l3 as by means of a mounting ferrule -30.As thus supported, the outer capacitance-member 21 is disposed betweenthe actuating device 13 and the variable inductance device 11 and insubstantially coaxially aligned relation with these devices. The innercapacitance member 28 comprises a substantially cylindrical bodyconstituting an axial projection of a carrier member or plunger 35 towhich further reference will 'bemade hereinaf ter. The inner capacitancemember "28 is of a size to'be axiallymovable into "closely spacedtelescoping relation to the outer capacitance member 21. Although theinner capacitance member 28 could bea hollow metal member or sleeve, itis preferably a solid cylindrical body as here shown. The innercapacitance member 28 is made of a metal having 'goo'dielectricalconductivity, preferably a non-ferrous metal such as copper-or aluminumand "preferably has a thin plating ofsilver (notchown) thereon.

This inner capacitance member 28 is provided with "an insulating cover32 for insulating the same from metallic contact with the outercapacitance member 2? when the inner capacitance member is moved axiallyinto the "latter. The covering 32 can bemade of any suitable ins'ulatingmaterial or plastic such as polystyrene and can be molded in placeorotherwiseaffixed to the inner capacitance member in surroundingrelation'thereto.

'In a dition 'to forming a part of the variable capacitance device l2,the inner capacitance member 28 also forms-a support 'for the coremember 1'! and connects the latter wit v th -c r rier member 3|. Thecore member I! is here shown as being mounted on the inner capacitancemember 28 by having one of its ends engaged in an opening 33 of thiscapacitance member.

To provide for connection of an electric circuit with the outercapacitance member 21, this member preferably has a terminal lug 21formed on the inner end thereof which extends through a radial slotfiZ 9of the mounting sleeve 29.

The actuating device l3 serving both the variable inductance device I land the variable capacitance device I2, constitutes an important part:O-f the present invention and comprises a pair of coaxially nestedouter and inner sleeves 35 and 36,. and the above-mentioned carriermember or plunger 'tfl'which is axially slidable in the inner sleeve.The outer sleeve 35 is provided a hollow stemi-si avhichthe actuatingdevice is adapted to be mounted on the upright portion N of the supportP4. The hollow stem 3i projects forwardly through an opening 38 of theupright wait M and is an externally thereaded stem to which a nut -cilis applied in clamping cooperation with the wall for mounting theactuating device thereon. "The outer sleeve 35, including the hollowstem portion 3''! thereof and the clamping nut 39 are electricallyisolated from the upright wall portion 14* as by means of the interposedinsulating bushing it and the interposed insulating disc M.

The'inner sleeve '35 constitutes a driving sleeve which-is rotatable inthe outer sleeve 35 and is retained therein by means of a retaining ring'42 engaged in an internal groove 53 provided adjacent the inner end ofthe outer sleeve. The inner sleeve 36 includes an axial shaft portion Mwhich projects forwardly through the hollow stem portion 31-andisjournalled therein. Rotation can be imparted to the inner sleeve 36 bysuitable actuating means cooperating with the shaft portion 44,, such asthe manually operable knob' lbshown in this instance andwhich isconnected with the shaft portion by means of the transverse 'pin 46.

"The outer sleeve 35 is provided with an axial slot nformed in the wallthereof and the inner sleeve 3'6 i'sprovided with a helical slot 48formed in the wall'thereof and extending in crossing relation to the.axial slot. A follower means which is "here shown in the form of aradial pin 49 engages in both of these slots at their point of crossingrelation and is connected with the carrier member3l as by engagement inan opening 50 thereof. The engagement of the followerpin 49 in the axialslot ii .hold's the-carrier member 3'! against rotation in the "innersleeve .36, and the engagement of this pin'in 'thehelical slot 48renders the carrier member axially movable in response to the wedgingaction produced by the helical slot .on the pin in'resp'on's'e torotation of the inner sleeve.

'From the construction of the tuning device 16 asshownin the drawing andabove described, it will be seen "that the coretmember .H and the innercapacitance meniber'flg are both carried and Lactuatedby the carriermember 3i. It will also be seen that the axial movement imparted to thecarrier member 3 l by rotation'of the inner sleeve 36 causes asimultaneous axial movement of the core member I? and 'the'innercapacitance member 2 8 inwardly oroutwardly dependingupcn the directionin which the sleeve 35 is rotated. When 'the sleeve is rotated in onedirection, the core member 11 will 'bemoved inwardly into the inner coil{[5 -of the variable inductance device II to vary the inductance valuethereof, and the inner capacitance element 28 will be moved into theouter capacitance member 21 to vary the capacitance value of thevariable capacitance device [2. Upon rotation of the sleeve 36 intheopposite direction, the core member I! will be retracted from thevariable inductance device I i and the inner capacitance member 28 willbe retracted from the outer capacitance member 2'! and during suchretracting movement, the inner capacitance member 28 will move into theactuating device H) where it will be substantially fully shielded by thelatter.

The axial and helical slots 4'! and 48 of the actuating device I3 are ofa length appropriate for the axial movement desired to be imparted tothe core member I 1 and the inner capacitance member 28. The helicalslot as is here shown as being approximately 180 in arcuate extentalthough, if desired, it can be of a greater or shorter arcuate length.The slope angle of the helical slot 48 can be of any desired valuesuitable to give the core member I! and the inner capacitance member 28a desired rate of axial movement in response to the rotary movement ofthe driving sleeve 36.

The actuating device [3 preferably also includes visual indicating meanssuch as the graduated dial 52 and the pointer 53 which cooperates withthe dial and is arcuately movable adjacent thereto by the knob 45. Thedial 52 carries an arcuate series of graduations 54 and is adapted to bemounted on the upright wall portion M by the clamping action of the nut39.

The improved tuning device it can be used in various radio circuits suchas oscillation circuits of the so-called tank type and, as one exampleof such use, the drawing shows certain conventional radio circuitconnections or components which need be only briefly described. Theseradio circuit components comprise an antenna 55 with which the terminal22 of the outer coil N5 of the variable inductance device I I isconnected by the conductor 56, and a ground 5'! with which the terminalsIQ and 2! are connected by conductor means These radio circuitcomponents also include an electron tube 59 having a grid Gil with whichthe terminal of the variable inductance device i l and the terminal lug2'! of the variable capacitance device 12 are connected by conductormeans 65. Additionally, these radio circuit components include a ground62 with which the actuating device :3 is connected as represented by theconductor G3.

From the foregoing detailed description and the accompanying drawing itwill now be readily understood that this invention provides an improvedradio circuit tuning device which can be economically produced and whichcan be made of such small and compact size that it can be used toadvantage in radio apparatus or the like which is of a small orminiature size. It will also be understood that this improved tuningdevice is applicable to a wide range of signal frequencies and since therotary travel of the driving sleeve 36 can extend for a full 360 degreesor greater, the graduations of the reference scale {i l of the dial 52can be relatively widely spaced apart for easier and more accuratereading of the different settings.

Although the improved radio circuit tuning device of this invention hasbeen illustrated and described herein to a somewhat detailed extent, itwill be understood, of course, that the invention is not to be regardedas being limited corre- 6 spondingly in scope, but includes all changesand modifications coming within the terms of the claims hereof.

Having thus described my invention, I claim:

1. In a tuning device of the character described, a capacitance element,inductance coil means in adjacent substantially aligned relation to saidcapacitance element, a pair of nested inner and outer sleeves located inadjacent substantially aligned relation to said capacitance element andinductance coil means and one of said sleeves being rotatable relativeto the other sleeve, one of said sleeves having an axial slot in thewall thereof and the other having a helical slot in the wall thereofextending in crossing relation to said axial slot, a carrier memberslidably supported by said nested sleeves for movement in an axialdirection, core means connected with said carrier member for movementthereby into the magnetic field of said inductance coil means, a secondcapacitance element connected with said carrier member for movementthereby into a capacitance relation to the first-mentioned capacitanceelement, and follower means connected with said carrier member andengaging in both slots substantially at their point of crossingrelation.

2. In a circuit tuning device of the character described, a pair ofsleeves disposed in substantially coextensive coaxial nested relationand comprising a fixed outer sleeve having a hollow stem portion adaptedfor connection with a support and an inner driving sleeve rotatable insaid outer sleeve and having a shaft portion extending through saidhollow stem portion, a tubular capacitance element and a hollowinductance coil means disposed in adjacent substantially coaxiallyaligned relation to said nested sleeves, insulating sleeve meanssupporting said capacitance element and said hollow coil means in saidcoaxially aligned relation, a plunger axially slidable in said nestedsleeves, a second capacitance element and a core means connected withsaid plunger for movement thereby into the first-mentioned capacitanceelement and said hollow coil means, said fixed sleeve having an axialslot in the wall thereof and said driving sleeve having a helical slotin the wall thereof extending in crossing relation to said axial slot,and follower means connected with said plunger and engaging in bothslots substantially at their point of crossing relation.

3. In a circuit tuning device of the character described, a supporthaving an opening therein, a pair of sleeves disposed in substantiallycoextensive coaxial nested relation and comprising a fixed outer sleevehaving a hollow stem portion of relatively reduced size extendingthrough the opening of said support and an inner driving sleeverotatable in said outer sleeve and having a shaft portion extendingthrough said hollow stem portion, retaining means engaging said hollowstem portion and cooperating with said support for connecting said fixedsleeve with the latter, a tubular capacitance element and a hollowinductance coil means disposed in adjacent substantially coaxiallyaligned relation to said nested sleeves, insulating sleeve meanssupporting said capacitance element and said hollow coil means in saidcoaxially aligned relation, a plunger axially slidable in said nestedsleeves, a second capacitance element and a core means connected withsaid plunger for movement thereby into the first-mentioned capacitanceelement and said hollow coil means, said fixed sleeve having an axialslot. in the wall thereofv and said driving sIeeve having a helical slotin the Wall thereof extending in crossing relation to said. axial slot,v

follower means connected with said plunger and engagingin bothlslotssubstantially at their point of 'orossing relation, actuating meansconnected with said shaft portion for imparting rotary movement to saidinner sleeve, stationary indicating means connected with said supportand extending arcuately around the axis of said shaft portion, and otherindicating means movable by said shaft portion and cooperating with saidstationary indicating means.

GEORGE E. MORTON.

References Cited in. the. file ofw this. patent UNITED STATES PATENTS 5Number Number Name Date- OBrien Apr. 9; 1946 Burroughes Mar. 28'; I950FOREIGN PATENTS Country Date- GreatBritain' i- June 5; 1944

